/**
 * Copyright Frank Cheung <frank@ajaxjs.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.ajaxjs.js.jsonparser.lexer;

import com.ajaxjs.js.jsonparser.JsonParseException;

/**
 * 字符串 Token
 * @author Frank Cheung frank@ajaxjs.com
 */
public class StringToken extends Token {
	/**
	 * 
	 * @param value
	 */
	public StringToken(String value) {
		super(0, "STR", "字符串", null, value);
	}
	
	/**
	 * 转义
	 * 
	 * @param str
	 * @return
	 */
	static String unescape(String str) {
		StringBuilder sb = new StringBuilder();

		for (int i = 0; i < str.length(); i++) {
			char c = str.charAt(i);
			
			if (c == '\\') {
				c = str.charAt(++i);// 游标前进一个字符

				switch (c) {
					case '"':
						sb.append('"');
						break;
					case '\\':
						sb.append('\\');
						break;
					case '/':
						sb.append('/');
						break;
					case 'b':
						sb.append('\b');
						break;
					case 'f':
						sb.append('\f');
						break;
					case 'n':
						sb.append('\n');
						break;
					case 'r':
						sb.append('\r');
						break;
					case 't':
						sb.append('\t');
						break;
					case 'u':
						String hex = str.substring(i + 1, i + 5);
						sb.append((char) Integer.parseInt(hex, 16));
						i += 4;
						break;
					default:
						throw new JsonParseException("“\\”后面期待“\"\\/bfnrtu”中的字符，结果得到“" + c + "”");
				}
			} else {
				sb.append(c);
			}
		}

		return sb.toString();
	}
}
